Viruses and bacteria can both cause disease, but they are radically different when it comes to their structure, reproduction and just about anything else. Bacteria are made up of just one basic cell possessing DNA, cell walls, ribosomes and cytoplasm. Viruses are tiny in comparison, simply consisting of a strand of genetic information (as DNA or RNA) encased in protein. In this sense, viruses are not considered to be living things. Bacteria reproduce asexually, dividing into two identical cells. Viruses, meanwhile, multiply by infi ltrating their host’s cells and tricking them into producing copies of the virus. Viral infections are harder to cure since the virus is taken up inside the patient’s cells, while bacterial infections can usually be treated with antibiotics.